test: add store, parse, and diff specs

Problem: need test coverage for core data operations, inline
metadata parsing, and buffer diff algorithm.

Solution: add busted specs for store CRUD, round-trip
preservation, parse body/command_add with configurable date
syntax, and diff create/delete/update/copy/move operations.

spec/diff_spec.lua

@@ -0,0 +1,139 @@
+require('spec.helpers')
+
+local config = require('todo.config')
+local store = require('todo.store')
+
+describe('diff', function()
+  local tmpdir
+  local diff = require('todo.diff')
+
+  before_each(function()
+    tmpdir = vim.fn.tempname()
+    vim.fn.mkdir(tmpdir, 'p')
+    vim.g.todo = { data_path = tmpdir .. '/tasks.json' }
+    config.reset()
+    store.unload()
+    store.load()
+  end)
+
+  after_each(function()
+    vim.fn.delete(tmpdir, 'rf')
+    vim.g.todo = nil
+    config.reset()
+  end)
+
+  describe('parse_buffer', function()
+    it('parses headers and tasks', function()
+      local lines = {
+        'School',
+        '/1/  Do homework',
+        '/2/  ! Read chapter 5',
+        '',
+        'Errands',
+        '/3/  Buy groceries',
+      }
+      local result = diff.parse_buffer(lines)
+      assert.are.equal(6, #result)
+      assert.are.equal('header', result[1].type)
+      assert.are.equal('School', result[1].category)
+      assert.are.equal('task', result[2].type)
+      assert.are.equal(1, result[2].id)
+      assert.are.equal('Do homework', result[2].description)
+      assert.are.equal('School', result[2].category)
+      assert.are.equal('task', result[3].type)
+      assert.are.equal(1, result[3].priority)
+      assert.are.equal('blank', result[4].type)
+      assert.are.equal('Errands', result[6].category)
+    end)
+
+    it('handles new tasks without ids', function()
+      local lines = {
+        'Inbox',
+        '  New task here',
+      }
+      local result = diff.parse_buffer(lines)
+      assert.are.equal(2, #result)
+      assert.are.equal('task', result[2].type)
+      assert.is_nil(result[2].id)
+      assert.are.equal('New task here', result[2].description)
+    end)
+  end)
+
+  describe('apply', function()
+    it('creates new tasks from buffer lines', function()
+      local lines = {
+        'Inbox',
+        '  First task',
+        '  Second task',
+      }
+      diff.apply(lines)
+      store.unload()
+      store.load()
+      local tasks = store.active_tasks()
+      assert.are.equal(2, #tasks)
+      assert.are.equal('First task', tasks[1].description)
+      assert.are.equal('Second task', tasks[2].description)
+    end)
+
+    it('deletes tasks removed from buffer', function()
+      store.add({ description = 'Keep me' })
+      store.add({ description = 'Delete me' })
+      store.save()
+      local lines = {
+        'Inbox',
+        '/1/  Keep me',
+      }
+      diff.apply(lines)
+      store.unload()
+      store.load()
+      local active = store.active_tasks()
+      assert.are.equal(1, #active)
+      assert.are.equal('Keep me', active[1].description)
+      local deleted = store.get(2)
+      assert.are.equal('deleted', deleted.status)
+    end)
+
+    it('updates modified tasks', function()
+      store.add({ description = 'Original' })
+      store.save()
+      local lines = {
+        'Inbox',
+        '/1/  Renamed',
+      }
+      diff.apply(lines)
+      store.unload()
+      store.load()
+      local task = store.get(1)
+      assert.are.equal('Renamed', task.description)
+    end)
+
+    it('handles duplicate ids as copies', function()
+      store.add({ description = 'Original' })
+      store.save()
+      local lines = {
+        'Inbox',
+        '/1/  Original',
+        '/1/  Copy of original',
+      }
+      diff.apply(lines)
+      store.unload()
+      store.load()
+      local tasks = store.active_tasks()
+      assert.are.equal(2, #tasks)
+    end)
+
+    it('moves tasks between categories', function()
+      store.add({ description = 'Moving task', category = 'Inbox' })
+      store.save()
+      local lines = {
+        'Work',
+        '/1/  Moving task',
+      }
+      diff.apply(lines)
+      store.unload()
+      store.load()
+      local task = store.get(1)
+      assert.are.equal('Work', task.category)
+    end)
+  end)
+end)

spec/helpers.lua

@@ -0,0 +1,38 @@
+local plugin_dir = vim.fn.getcwd()
+vim.opt.runtimepath:prepend(plugin_dir)
+vim.opt.packpath = {}
+
+vim.cmd('filetype on')
+
+local M = {}
+
+---@param lines? string[]
+---@return integer
+function M.create_buffer(lines)
+  local bufnr = vim.api.nvim_create_buf(false, true)
+  vim.api.nvim_buf_set_lines(bufnr, 0, -1, false, lines or {})
+  return bufnr
+end
+
+---@param bufnr integer
+function M.delete_buffer(bufnr)
+  if bufnr and vim.api.nvim_buf_is_valid(bufnr) then
+    vim.api.nvim_buf_delete(bufnr, { force = true })
+  end
+end
+
+---@param bufnr integer
+---@param ns integer
+---@return table[]
+function M.get_extmarks(bufnr, ns)
+  return vim.api.nvim_buf_get_extmarks(bufnr, ns, 0, -1, { details = true })
+end
+
+---@return string
+function M.tmpdir()
+  local dir = vim.fn.tempname()
+  vim.fn.mkdir(dir, 'p')
+  return dir
+end
+
+return M

spec/parse_spec.lua

@@ -0,0 +1,117 @@
+require('spec.helpers')
+
+local config = require('todo.config')
+
+describe('parse', function()
+  before_each(function()
+    vim.g.todo = nil
+    config.reset()
+  end)
+
+  after_each(function()
+    vim.g.todo = nil
+    config.reset()
+  end)
+
+  local parse = require('todo.parse')
+
+  describe('body', function()
+    it('returns plain description when no metadata', function()
+      local desc, meta = parse.body('Buy groceries')
+      assert.are.equal('Buy groceries', desc)
+      assert.are.same({}, meta)
+    end)
+
+    it('extracts due date', function()
+      local desc, meta = parse.body('Buy groceries due:2026-03-15')
+      assert.are.equal('Buy groceries', desc)
+      assert.are.equal('2026-03-15', meta.due)
+    end)
+
+    it('extracts category', function()
+      local desc, meta = parse.body('Buy groceries cat:Errands')
+      assert.are.equal('Buy groceries', desc)
+      assert.are.equal('Errands', meta.cat)
+    end)
+
+    it('extracts both due and cat', function()
+      local desc, meta = parse.body('Buy milk due:2026-03-15 cat:Errands')
+      assert.are.equal('Buy milk', desc)
+      assert.are.equal('2026-03-15', meta.due)
+      assert.are.equal('Errands', meta.cat)
+    end)
+
+    it('extracts metadata in any order', function()
+      local desc, meta = parse.body('Buy milk cat:Errands due:2026-03-15')
+      assert.are.equal('Buy milk', desc)
+      assert.are.equal('2026-03-15', meta.due)
+      assert.are.equal('Errands', meta.cat)
+    end)
+
+    it('stops at duplicate key', function()
+      local desc, meta = parse.body('Buy milk due:2026-03-15 due:2026-04-01')
+      assert.are.equal('Buy milk due:2026-03-15', desc)
+      assert.are.equal('2026-04-01', meta.due)
+    end)
+
+    it('stops at non-meta token', function()
+      local desc, meta = parse.body('Buy milk for breakfast due:2026-03-15')
+      assert.are.equal('Buy milk for breakfast', desc)
+      assert.are.equal('2026-03-15', meta.due)
+    end)
+
+    it('rejects invalid dates', function()
+      local desc, meta = parse.body('Buy milk due:2026-13-15')
+      assert.are.equal('Buy milk due:2026-13-15', desc)
+      assert.is_nil(meta.due)
+    end)
+
+    it('preserves colons in description', function()
+      local desc, meta = parse.body('Meeting at 3:00pm')
+      assert.are.equal('Meeting at 3:00pm', desc)
+      assert.are.same({}, meta)
+    end)
+
+    it('uses configurable date syntax', function()
+      vim.g.todo = { date_syntax = 'by' }
+      config.reset()
+      local desc, meta = parse.body('Buy milk by:2026-03-15')
+      assert.are.equal('Buy milk', desc)
+      assert.are.equal('2026-03-15', meta.due)
+    end)
+
+    it('ignores old syntax when date_syntax is changed', function()
+      vim.g.todo = { date_syntax = 'by' }
+      config.reset()
+      local desc, meta = parse.body('Buy milk due:2026-03-15')
+      assert.are.equal('Buy milk due:2026-03-15', desc)
+      assert.is_nil(meta.due)
+    end)
+  end)
+
+  describe('command_add', function()
+    it('parses simple text', function()
+      local desc, meta = parse.command_add('Buy milk')
+      assert.are.equal('Buy milk', desc)
+      assert.are.same({}, meta)
+    end)
+
+    it('detects category prefix', function()
+      local desc, meta = parse.command_add('School: Do homework')
+      assert.are.equal('Do homework', desc)
+      assert.are.equal('School', meta.cat)
+    end)
+
+    it('ignores lowercase prefix', function()
+      local desc, meta = parse.command_add('hello: world')
+      assert.are.equal('hello: world', desc)
+    end)
+
+    it('combines category prefix with inline metadata', function()
+      local desc, meta = parse.command_add('School: Do homework due:2026-03-15')
+      assert.are.equal('Do homework', desc)
+      assert.are.equal('School', meta.cat)
+      assert.are.equal('2026-03-15', meta.due)
+    end)
+  end)
+end)

spec/store_spec.lua

@@ -0,0 +1,189 @@
+require('spec.helpers')
+
+local config = require('todo.config')
+local store = require('todo.store')
+
+describe('store', function()
+  local tmpdir
+
+  before_each(function()
+    tmpdir = vim.fn.tempname()
+    vim.fn.mkdir(tmpdir, 'p')
+    vim.g.todo = { data_path = tmpdir .. '/tasks.json' }
+    config.reset()
+    store.unload()
+  end)
+
+  after_each(function()
+    vim.fn.delete(tmpdir, 'rf')
+    vim.g.todo = nil
+    config.reset()
+  end)
+
+  describe('load', function()
+    it('returns empty data when no file exists', function()
+      local data = store.load()
+      assert.are.equal(1, data.version)
+      assert.are.equal(1, data.next_id)
+      assert.are.same({}, data.tasks)
+    end)
+
+    it('loads existing data', function()
+      local path = config.get().data_path
+      local f = io.open(path, 'w')
+      f:write(vim.json.encode({
+        version = 1,
+        next_id = 3,
+        tasks = {
+          {
+            id = 1,
+            description = 'Todo one',
+            status = 'pending',
+            entry = '2026-01-01T00:00:00Z',
+            modified = '2026-01-01T00:00:00Z',
+          },
+          {
+            id = 2,
+            description = 'Todo two',
+            status = 'done',
+            entry = '2026-01-01T00:00:00Z',
+            modified = '2026-01-01T00:00:00Z',
+          },
+        },
+      }))
+      f:close()
+      local data = store.load()
+      assert.are.equal(3, data.next_id)
+      assert.are.equal(2, #data.tasks)
+      assert.are.equal('Todo one', data.tasks[1].description)
+      assert.are.equal('done', data.tasks[2].status)
+    end)
+
+    it('preserves unknown fields', function()
+      local path = config.get().data_path
+      local f = io.open(path, 'w')
+      f:write(vim.json.encode({
+        version = 1,
+        next_id = 2,
+        tasks = {
+          {
+            id = 1,
+            description = 'Todo',
+            status = 'pending',
+            entry = '2026-01-01T00:00:00Z',
+            modified = '2026-01-01T00:00:00Z',
+            custom_field = 'hello',
+          },
+        },
+      }))
+      f:close()
+      store.load()
+      local task = store.get(1)
+      assert.is_not_nil(task._extra)
+      assert.are.equal('hello', task._extra.custom_field)
+    end)
+  end)
+
+  describe('add', function()
+    it('creates a task with incremented id', function()
+      store.load()
+      local t1 = store.add({ description = 'First' })
+      local t2 = store.add({ description = 'Second' })
+      assert.are.equal(1, t1.id)
+      assert.are.equal(2, t2.id)
+      assert.are.equal('pending', t1.status)
+      assert.are.equal('Inbox', t1.category)
+    end)
+
+    it('uses provided category', function()
+      store.load()
+      local t = store.add({ description = 'Test', category = 'Work' })
+      assert.are.equal('Work', t.category)
+    end)
+  end)
+
+  describe('update', function()
+    it('updates fields and sets modified', function()
+      store.load()
+      local t = store.add({ description = 'Original' })
+      local original_modified = t.modified
+      store.update(t.id, { description = 'Updated' })
+      local updated = store.get(t.id)
+      assert.are.equal('Updated', updated.description)
+      assert.is_not.equal(original_modified, updated.modified)
+    end)
+
+    it('sets end timestamp on completion', function()
+      store.load()
+      local t = store.add({ description = 'Test' })
+      assert.is_nil(t['end'])
+      store.update(t.id, { status = 'done' })
+      local updated = store.get(t.id)
+      assert.is_not_nil(updated['end'])
+    end)
+  end)
+
+  describe('delete', function()
+    it('marks task as deleted', function()
+      store.load()
+      local t = store.add({ description = 'To delete' })
+      store.delete(t.id)
+      local deleted = store.get(t.id)
+      assert.are.equal('deleted', deleted.status)
+      assert.is_not_nil(deleted['end'])
+    end)
+  end)
+
+  describe('save and round-trip', function()
+    it('persists and reloads correctly', function()
+      store.load()
+      store.add({ description = 'Persisted', category = 'Work', priority = 1 })
+      store.save()
+      store.unload()
+      store.load()
+      local tasks = store.active_tasks()
+      assert.are.equal(1, #tasks)
+      assert.are.equal('Persisted', tasks[1].description)
+      assert.are.equal('Work', tasks[1].category)
+      assert.are.equal(1, tasks[1].priority)
+    end)
+
+    it('round-trips unknown fields', function()
+      local path = config.get().data_path
+      local f = io.open(path, 'w')
+      f:write(vim.json.encode({
+        version = 1,
+        next_id = 2,
+        tasks = {
+          {
+            id = 1,
+            description = 'Todo',
+            status = 'pending',
+            entry = '2026-01-01T00:00:00Z',
+            modified = '2026-01-01T00:00:00Z',
+            _gcal_event_id = 'abc123',
+          },
+        },
+      }))
+      f:close()
+      store.load()
+      store.save()
+      store.unload()
+      store.load()
+      local task = store.get(1)
+      assert.are.equal('abc123', task._extra._gcal_event_id)
+    end)
+  end)
+
+  describe('active_tasks', function()
+    it('excludes deleted tasks', function()
+      store.load()
+      store.add({ description = 'Active' })
+      local t2 = store.add({ description = 'To delete' })
+      store.delete(t2.id)
+      local active = store.active_tasks()
+      assert.are.equal(1, #active)
+      assert.are.equal('Active', active[1].description)
+    end)
+  end)
+end)